Ellipsometric studies of opal crystals

Abstract

Spectroscopic ellipsometry investigations have been performed on synthetic opal crystals containing SiO2 spheres having a diameter of D∼250 nm. The optical features in the spectra of ellipsometric parameters Ψ and Δ were observed in the region of stop band (500-550 nm). The ellipsometric spectra were separated due to diffraction and specular reflection. The data were interpreted by using effective homogeneous and stacked multi-layer media models. The average index of refraction of the opal photonic crystal was estimated in the first model and the angle-resolved spectra were qualitatively described by the second model. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.